fix: use TotalSeconds for operation latency measurement in SloContext

Author: polRk

slo/src/Internal/SloContext.cs

@@ -233,12 +233,12 @@ Task ShootingTask(RateLimiter rateLimitPolicy, string operationType,
                         {
                             errorsTotal.WithLabels(statusCode.StatusName()).Inc();
                             operationsFailureTotal.Inc();
-                            operationLatencySeconds.WithLabels("err").Observe(sw.ElapsedMilliseconds / 1000);
+                            operationLatencySeconds.WithLabels("err").Observe(sw.Elapsed.TotalSeconds);
                         }
                         else
                         {
                             operationsSuccessTotal.Inc();
-                            operationLatencySeconds.WithLabels("success").Observe(sw.ElapsedMilliseconds / 1000);
+                            operationLatencySeconds.WithLabels("success").Observe(sw.Elapsed.TotalSeconds);
                         }
                     }, cancellationTokenSource.Token);
                 }